Oxygen and Air Travel
To find out whether you require supplemental oxygen, your doctor will evaluate your current health and review your health history, including your past experience with air travel. If you've had breathing problems before while flying, you're at risk for experiencing them again.
The doctor will also give you a physical exam, and you'll undergo pulmonary function testing to determine how well your lungs are working. In addition, you may be asked to take a test called the hypoxia altitude simulation test (HAST).
The HAST lasts 20 minutes and involves breathing a mixture of gases through a tight-fitting mask or mouthpiece. The mixture provides a 15.1 percent concentration of oxygen, which simulates the level of oxygen you would get breathing at 8,000 feet. During the test, your vital signs (heart rate, respiration rate, blood pressure, temperature) are monitored for any changes. In addition, an EKG is used to monitor your heart and a pulse oximeter to check your oxygen saturation level.
At the start of the test, and again at the end, blood samples will be taken and analyzed to determine the adequacy of oxygen in your blood, as indicated by the "partial pressure of oxygen," or PaO2. Your PaO2 is a number expressed as a unit of measurementmm Hg. At sea level, where the air you breathe has a 21 percent concentration of oxygen, a normal PaO2 is between 75 and 100 mm Hg. As the concentration of oxygen in your blood declines, so will the PaO2. How much it declines determines your risk for severe hypoxemia and, consequently, your need for oxygen.
If your PaO2 at the end of the test is:
- greater than 55 mm Hg, you won't need oxygen on the trip
- less than 50 mm Hg, you will need oxygen during the flight
- between 50 and 55 mm Hg, you will have to repeat the test with activity such as walking added to determine your need